In Nostr, your relay gets to make and enforce it’s own content policies just as easily as it does on AP
And yet they don’t.
If you as a user can connect to multiple relays, then most people will do that, making the act of an admin banning a bigot on one relay pointless, because the bigot will still get through on other relays, and once they’re blocked on enough relays, they’ll just make another throw away account. Which means most admins won’t bother acting except in the most egregious cases, leaving it up to the users to deal with their own blocks.
I agree, there needs to be an answer here that lets people keep their identities tied to them rather than an instance, but the nostr approach isn’t it. It just leads to everyone for themselves, which is fine for some people, but it’s exactly what many other folk were trying to escape by coming to the fediverse in the first place.